All settings changedsettings-reference
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443443### `fastMode`
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445Turn [fast mode](https://code.claude.com/docs/en/fast-mode.md) on for sessions where it's available, for interactive work like rapid iteration or live debugging where you want speed at a higher cost per token. You don't usually edit this key by hand: running `/fast` writes `fastMode: true` to `~/.claude/settings.json`, and running it again to turn fast mode off removes the key. Fast mode runs only on Opus 5.5, Opus 5, and Opus 4.8: turning it on from another model switches you to Opus, and switching to an unsupported model turns it off. See [Switch models while fast mode is on](https://code.claude.com/docs/en/fast-mode.md#switch-models-while-fast-mode-is-on).
445Turn [fast mode](https://code.claude.com/docs/en/fast-mode.md) on for sessions where it's available, for interactive work such as rapid iteration or live debugging where you want speed at a higher cost per token. You don't usually edit this key yourself. Running `/fast` writes `fastMode: true` to `~/.claude/settings.json`, and running it again to turn fast mode off removes the key.
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447Only Opus 5.5, Opus 5, and Opus 4.8 support fast mode. Running `/fast` from another model switches you to Opus, and switching to an unsupported model turns fast mode off. See [Switch models while fast mode is on](https://code.claude.com/docs/en/fast-mode.md#switch-models-while-fast-mode-is-on).
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447449* **Scope**: [`Any file`](#scopes)
448450* **Type**: Boolean
449451 * `true`: Claude Code turns fast mode on for sessions where it's available
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460462### `fastModePerSessionOptIn`
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462Normally, running `/fast` saves [`fastMode`](#fastmode) to a person's user settings, so fast mode is on at the start of every later session. Set this key to `true` to stop that: a saved `fastMode: true` no longer turns fast mode on at session start, and each person has to run `/fast` in each session they want it. Claude Code leaves the `fastMode` key in their file, so turning this key off restores the old behavior.
464Normally, running `/fast` saves [`fastMode`](#fastmode) to a person's user settings, so new sessions on a supported model start with fast mode on. Set this key to `true` to stop that: a saved `fastMode: true` no longer turns fast mode on at session start, and each person runs `/fast` in each session they want it. Claude Code leaves `fastMode` in their file, so turning this key off restores the old behavior.
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464466Owners on Team or Enterprise plans can deploy it organization-wide through [server-managed settings](https://code.claude.com/docs/en/server-managed-settings.md). When managed settings set the key, `/fast on` is refused outside interactive terminal sessions and reports that your organization has disabled fast mode. That covers [non-interactive mode](https://code.claude.com/docs/en/headless.md), the [VS Code extension](https://code.claude.com/docs/en/vs-code.md), and [cloud sessions](https://code.claude.com/docs/en/claude-code-on-the-web.md).
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466468* **Scope**: [`Any file`](#scopes)
467469* **Type**: Boolean
468470 * `true`: a saved `fastMode: true` no longer turns fast mode on at session start, so each person runs `/fast` in each session they want it; a `fastMode: true` passed with `--settings` still counts for that session unless managed settings set this key
469 * `false`: a saved `fastMode: true` turns fast mode on at the start of every later session
471 * `false`: a saved `fastMode: true` turns fast mode on at the start of each new session on a supported model
470472* **Default**: `false`
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472474```json settings.json theme={null}
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33993401To hide all attribution, set `attribution` to `false`. In a settings file that earlier versions also read, set [`commit`](#attribution-commit) and [`pr`](#attribution-pr) to empty strings and [`sessionUrl`](#attribution-sessionurl) to `false` instead.
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3401This example replaces the commit attribution, removes pull request attribution, and drops
3403This example replaces the commit attribution, removes pull reques
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